Frequency multiplication



Patented Dec. 13, 1932 UNITED STATES,

PATENT OFFICE YMVEIYIDELY osnosor BERLI GERMANY, Ass'IGNoR TO TELEFUNKENensnnrisoriarr FUR DRAHTLOSE TELEGRAPHIE MLB. I-L, or BERLIN, GERMANY, ACORPORATION 1 or onnmm FREQUENCY MULTIPLICATION Application filedDecember 2, 1930, Serial 110,499,450, and in. Germany December 2, 1929'.

It is known in the prior art that electric valves may be used notonlyfor rectification of the current, but alsofor frequencymultiplication. The circuit schemes adapted to this end are generallyknown and need not be enlarged upon here. Fundamentally, they are basedupon thefact that the wave of the valve current, apart from the directcurrent component and the fundamental wave of the alternating current,contains a number of harmonics, which, by the aid of suitable couplingmeans and suitably tuned circuits, may be fed to the load or consumerapparatus.

The present invention has for an object the provision of methods andmeans for amplifying these overtones or higher harmonics and/or toincrease their number.

If the filament of a valve which works as a rectifier feeding thermionictubes is fed with alternating current, owing to this filament or heatingcurrent there arisesin the valve, for instance, when the filament isgrounded centrally, an additional superposed current of double frequencywhich proves troublesome in the thermionic tubes as it appears in theform of a beat note of double frequency. Many attempts have been made toobviate this modulative action of the filament heating alternatingcurrent in the rectifier as far as feasible.

Now, according to this invention, quite distinct from the foregoingschemes, the modulating action of the alternating current heating thefilament is utilized in the operation of electric valves when working aslow or high frequency converters, by choosing the frequency of theheating or filament current so that in relation to the fundamental wavea practical improvement of the desired frelation, there is produced inthe valve current, I

tri pling.

Usingfor'heating the frequency n =5,000 then the influence of theheating by virtueof a modulating frequency of n =10,000 nanifests itselfin this way that outside the fundamental wave of n =l.0,000 there isobtained a side wave of n =20,000 and another side wave having afrequency n =zero, in other words, an additional direct currentco-mponent. In a sLmilar manner other frequencies could be chosen forthe heating in order to secure the desired amplification of acertainselected or preferential overtone.

In order that the amplitudes of the harmonies thus produced may be madeas large as possible, it is advisable to so manufacture the filamentthat it will require as high a filament potential as possible, and touse, moreover, valves presentzng a characteristic of maximum slope. forexample, the well known mercury-vapor tubes furnished with a heatedwherein Figure 1 illustrates a frequency multiplier wherein currents oflike frequency apply to the input circuit and to the cathode heatingcircuit, and

Figure 2 illustrates a similar systemwherein currents of differentfrequency are applied "to the input and filament heating circuits of avacuum tube frequency multiplier.

Turning to Figure 1, alternating energy from an oscillator 2 of suitableconstruction is applied to the input circuit of electron dischargedevice 4, througlithe action of transformer 6 and-to the cathode heatingcircuit thereofthrough the action of transformer8.

The frequency of currents applied, it is to be clearly understood, mayeither be a low frequency, such as an audio frequency, a superaudiblefrequency, or a radio frequency, depending upon the desired output. Inthe output circuit 8 of electron discharge device 4, there will appear,in accordance with what has been said hereinbefore, a com onent equal tothe third harmonic of the requency of oscillator 2,'which harmonic maybe accentuated by suitably tuning output circuit 10 as indicated.

The output of frequency multiplier 4 may be fed to any suitableutilization circuit, or fed in a similar fashion to a similarlyconnected frequency multiplier for still further increasing thefrequency of alternating current originally derived from oscillator 2.

In Figure 2, energy from'a master oscillator 2 of any desiredconstruction, is fed to afrequency multiplier 12 which may be, ifdesired, of the type shown in Figure 1. The

output of frequency multiplier 12 is fed to the input side of electrondischarge device frequency multiplier 14; whereas, energy of a frequencyof the same order corresponding to that of oscillator'2 is fed to thecathode circuit thereof through transformer 16 as shown. By suitablytuning the output circuit 18, energy of desired frequencies, asindicated, may be derived for direct use or for further frequencymultiplication and ampli- 'fication.

It is to be clearly understood, that the sup- ,ply to electron emissiontube 14 may be reversed if desired, the relatively low frequency beingapplied to the input electrodes through the action of transformer 18,and,

the relatively high frequency ener y being applied to the filament.Moreover, if desired, the filament or cathode may be of theindirectlyvheated type although it is'preferred that the cathode consistmerely of a high resistance conductor.

I claim: 7 a a 1. A high frequency producing means com-v prising asourceof oscillations and means for multiplying the frequency of saidoscillations including, a thermionic discharge device having input andoutput electrodes including a heated cathode, a transformer having itsprimary winding connected to said oscillator and its secondary windingconnected in series with the heated cathode of said tube, an inputcircuit including an inductance connected between the control electrodeof said tube and the electrical midpoint of said secondary winding ofsaid transformer, a second inductance connected with said oscillator andcoupled to said first named inductance, a circuit connected between theoutput electrodes of said tube,.and means in said output circuit fortuning the'same to a multiple of the frequency of said source.

' 2. An'arrangement as claimed in claim r ode V V MENDEL OSNOS.

